The proposed research will analyze the principal connections of dorsal cortex in the turtle, Pseudemys scripta. The organization of the projection of the dorsal lateral geniculate nucleus to dorsal cortex will be determined using both the orthograde and retrograde transport of horseradish peroxidase (HRP). The precise postsynaptic targets of dorsal cortex in the lateral geniculate, tectum, nucleus rotundus and anterior dorsal ventricular ridge will be determined using HRP-electron microscopic techniques. The organization of these projections will then be analyzed using both the orthograde and retrograde transport of HRP and autoradiographic techniques following restricuted injections in dorsal cortex. These studies will extend our detailed analysis of visual system in Pseudemys. Work completed to date indicates that turtle visual system shares many general features with mammalian visual systems, but contains fewer components and is more amenable to complete analysis. An important difference with the more familiar mammalian systems is that some of the projections in turtle visual system are not retinotopically organized. The proposed research will examine the organization of the major connections of dorsal cortex and focus particularly on the interaction of retinotopically and non-retinotopically organized projections.